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WARNING: The fuel system may be under pressure. If you hear
a hissing sound near the fuel filler door (Easy Fuel™ “no cap”
fuel system), do not refuel until the sound stops. Otherwise, fuel may
spray out, which could cause serious personal injury.
Flex Fuel Vehicle (FFV) fuel fill inlet
Flex fuel vehicles have a yellow bezel placed over the fuel fill inlet.
Choosing the right fuel
Use only UNLEADED FUEL and FUEL ETHANOL (Ed75–Ed85).
The use of leaded fuel is prohibited by law and could damage your
vehicle.
Your vehicle was not designed to use fuel or fuel additives with metallic
compounds, including manganese-based additives.
Note: Use of any fuel other than those recommended may cause
powertrain damage, a loss of vehicle performance, and repairs may not
be covered under warranty.
Octane recommendations
Your vehicle is designed to use
“Regular” unleaded gasoline with a
pump (R+M)/2 octane rating of 87.
We do not recommend the use of
gasolines labeled as “Regular” in
high altitude areas that are sold with octane ratings less than 87.
Do not be concerned if your engine sometimes knocks lightly. However, if
it knocks heavily under most driving conditions while you are using fuel
with the recommended octane rating, see your authorized dealer to
prevent any engine damage.
FFV engine
Your vehicle is designed to use Fuel Ethanol (Ed75–Ed85),“Regular”
unleaded gasoline or any mixture of the two fuels.
Use of other fuels such as Fuel Methanol may cause powertrain
damage, a loss of vehicle performance, and your warranty may be
invalidated.
Fuel quality
Do not add aftermarket fuel additive products to your fuel tank. It
should not be necessary to add any aftermarket products to your fuel
87
(R+M)/2 METHOD
2009 Navigator (nav)
Owners Guide, 2nd Printing
USA (fus)
Maintenance and Specifications
349